198 SWINE PRACTICE 



have been encountered in the testicle, and while these are not de- 

 structive to life, they damage the animal for breeding purposes. Sar- 

 comas and endotheliomas occasionally occur in the testicle, and are 

 usually primary. They are malignant tumors, however, and swine 

 with enlarged testicles are usually castrated. Fortunately, the oper- 

 ation is commonly performed before the tumors have metastasized, 

 and thus the lives of the swine are not sacrificed. 



PARASITES 



Screw Worm Infestation 



Infestation of the castration wounds with screw-worms (larvffi of 

 the Campsomyia macellaria) are verj^ common in the southern part 

 of the United States. These larvas burrow into the tissues, thus 

 mechanically injuring them and providing an avenue of entrance 

 for various bacteria. 



Lesions. — The principal lesions consist of an active, acute inflam- 

 mation with or without the production of pus. The surrounding 

 tissues are tumefied, hyperemic, hemorrhagic, and contain the larvae. 

 The extensive tumefaction developing within one or two days after 

 castration is the most evident symptom. On a close inspection, larvte 

 may be observed near or upon the surface, and by manipulation of 

 the lesion larvae may be forced out upon the surface. In cases 

 of screw-worm infestation there is a constant sero-sanguineous dis- 

 charge that by attracting the female fly favors repeated reinfestation. 



Treatment. — All that can be done in cases of screw-worm infesta- 

 tion is to support the strength and minister to the comfort of the 

 animal and prevent a further infestation from the deposition of more 

 eggs or larvae upon the wound and patiently wait for the investing 

 larvaj to reach the stage of development when they voluntarily leave 

 the wound to pupate in the ground. This occurs in three to five 

 days. 



The application of chloroform, naphthalene or other chemicals to 

 the wound is worse than useless. Such measures not only fail to 

 effect the removal of more than a small percentage of the larvse, but 

 they also irritate the highly sensitive tissues and greatly aggravate 

 the condition. 



None of the ordinary fiy-repellents has any deterrent effect upon 

 the female of the screw-worm fly in the presence of fresh blood, 

 either in recent wounds or in the discharge from screw-worm in- 

 fested wounds. However, a mixture composed of turpentine one 



